Is there a maximum number of Wi-Fi clients for a hotspot on the Raspberry Pi 3 (using the built-in Wi-Fi chip: Broadcom BCM43438)?
Regarding the software, I’m using
hostapd to manage the Access Point (on Raspbian).
The goal is to serve some PHP pages hosted on the Pi. There isn’t much computation and I think the bottleneck will be the number of clients supported by the hotspot.
I’m interested in the theoretical limit (e.g. the driver) as well as “experienced” limits.
my real world limit was 22 school kids in a classroom connected via there smartphones directly to the pi, now the access point was an open hotspot so the overhead was reduced drastically reduced as no encryption took place, also my pi-3 hadn't actually reached its limit as I'm sure more clients could have connected but was preforming rather sluggishly especially since every student had to click the same link at the same time to follow along.
I found that page loads took on average 2.5-3seconds for me. With the server being node.js http server and the content being returned the contents of a static file that were being stored in a string.
Correct answer by Mohammad Ali on December 28, 2020
This maximum number of Wi-Fi clients for a hotspot on the Raspberry Pi comes from this issue:
19 users with a Rpi 3b and 14 with a Rpi 3b+...
Different raspberry pi might have different limitations, like this issue:
Rpi4 4Gb RAM and I wasn't able to connect more than 8 devices...
this community post get a max number 14:
In both cases, I was able to connect 14 iPads to the AP.
Each time I tried to connect another device, it said wrong password. If a device was disconnected, it became available for another one to connect with > always the same limit of 14.
And if you need more, you can try other types of USB wifi sticks. It seems that the Ralink RT5370 can handle 189 clients which is the best one.
this post said we can get a maximum number 189:
Ralink RT5370: can handle 189 clients in total although I'm pretty sure performance would seriously drop above 40 stations. The limit cannot be changed due to overlapping with other tables stored in the same memory segment (ACL and pairwise key table).
Answered by Huan on December 28, 2020
On a off-line Pi configured as a hotspot thanks to Using your new Raspberry Pi 3 as a Wi-Fi access point with hostapd, I configured a hard coded 40 IP address limit. Seems to handle all of them properly. Because using web sockets for real-time interactions among all connected users on my Node.js app, I didn't try more.
More generally, I think that though the Pi may offer this feature with a bit of custom configuration, it is not optimized for this use. If you wan't to get satisfying Wi-Fi performance for each client, I suggest you restrain the number of physical clients: I mean, it's not because it's wireless that each client won't consume less resource about handling its connection / IP session.
Many routers offer to assign much more IP addresses, but that's about DHCP and assigning addresses to connected clients, not about handling 50 Wi-Fi traffic-wise distinct connections and contexts.
Ex: All Apple Airport stations have a limitations of 50 users for instance... see Compare AirPort family.
UPDATE: Months (!) later, eventually had the opportunity to test with lots of devices. It appears that the Pi 3B with a Jessie based Raspbian and its default WIFI component could accept no more than 32 MAC addresses, even with dnsmasq configured to allow up to 60 IPs.
Based on some Raspi Community Forums thread I assume this might be caused by a hard coded limit in the brcmfmac driver for the WIFI chip used on the board, still looking into this...
The Pi 3B+ with Stretch based Raspbian (9.4) could accept only up to 16 connections (same hostapd/dnsmasq config). As this is only half as much as the Pi 3B, I have nothing but hypothesis for this:
-either the Stretch embedded brcmfmac driver for the WIFI chip now limits to 16 MAC addresses (unlikely IMHO)
-or it is linked to the new WIFI chip used in the new board, now dual band 2,4/5 GHz when in client mode, but I could configure the AP only using the 2,4GHz, so only half the resources would be allocated therefore half the Pi 3B maximum capacity as a result (seems more plausible to me, but definitely not verified)
Answered by wiill on December 28, 2020
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